1. Field of the Invention
The present invention relates to a thin-type semiconductor package and fabrication method for use with for example a card-type external storage medium.
2. Description of the Related Art
As storage apparatuses for recording and storing data, for example memory cards are known. These memory cards have restrictions in their size (length, width, and thickness) and the like. Thus, semiconductor chips (IC chips) that are used with the memory cards should be compact. In addition, the memory cards in which the semiconductor chips are mounted should be thin.
To mount semiconductor chips in a limited space with a thickness of 1 mm or less, TAB (Tape Automated Bonding) method and flip chip method, COB (Chip On Board) method are known. As an example of the thin-type packages, a module shown in FIG. 1 is known. The module shown in FIG. 1 comprises a circuit board 2, an external connecting terminal 4, and a mold resin layer 5. A semiconductor chip 1 is mounted on a first main surface of the circuit board 2. The external connecting terminal 4 is connected to a second main surface of the circuit board 2 through a through-hole 3. The mold resin layer 5 seals and coats the mounting region of the semiconductor chip 1. In FIG. 1, reference numeral 6 is a bonding wire.
However, the above-mentioned TAB method is not a practical means from a cost point of view because of: (a) The fabrication cost of a carrier tape is relatively high. (b) Since dedicated metal mold and bonding tool corresponding to the package size are required in the mounting process, the assembling cost is relatively high.
On the other hand, in the above-mentioned flip chip mounting method and COB method, it is difficult to provide KGN (Known Good Die). Normally, the semiconductor chip 1 for use should have been burnt in. However, the burn-in technologies for chips have not been accomplished. Thus, since the semiconductor chip 1 that has not been burnt in should be used, there is a problem on the reliability. In other words, with this semiconductor chip (IC chip) 1, a defect that will take place in the near future cannot be predicted. In other words, the semiconductor chip 1 cannot be burnt in. Thus, in initial practical phases where the semiconductor chip 1 is mounted and thereby a module is formed, a trouble may take place.
Although the problem on the reliability of the semiconductor chip 1 may be solved by repairing or reworking it, the assembling cost will increase and many technical problems will arise. In particular, when a semiconductor chip 1 with many electrode terminals is mounted by the COB method, a long assembling time is required, thereby increasing the cost.
In the TAB method and COB method, a wider mounting area is required than in the flip chip mounting method. Thus, in the TAB method and COB method, the semiconductor package cannot be compactly formed. On the other hand, in the case of a packaged module where one surface is molded, bonding wires 6 often displace in the conventional (ordinary) transfer mold process. In addition, the connecting portions are often disengaged. Thus, there are problems on the reliability and yield. Moreover, since it is difficult to reduce the height of the bonding wires 6 to 0.1 mm or less with the current technologies, this restriction prevents thin-type packages from being accomplished. In addition, since a space for connecting the bonding wires 6 to the external connecting terminals 4 is required along with the mounting region of the semiconductor chip 1, the semiconductor package cannot be compactly formed.
A first object of the present invention is to provide a thin and compact semiconductor package.
A second object of the present invention is to provide a semiconductor package that is fabricated with relatively low cost and has high reliability.
A third object of the present invention is to provide a thin-type high-reliability semiconductor package suitable for a detachable memory portion for use with a memory card or the like.
A fourth object of the present invention is to provide a fabrication method for fabricating a compact semiconductor package with high yield.
A fifth object of the present invention is to provide a fabrication method for easily fabricating a semiconductor package with high reliability at a relatively low cost.
A sixth object of the present invention is to provide a fabrication method for easily fabricating a thin-type high-reliability semiconductor package suitable for a detachable memory portion for use with a memory card or the like.